Add backports.zoneinfo-0.2.1

lib/backports/zoneinfo/__init__.py

@@ -0,0 +1,49 @@
+__all__ = [
+    "ZoneInfo",
+    "reset_tzpath",
+    "available_timezones",
+    "TZPATH",
+    "ZoneInfoNotFoundError",
+    "InvalidTZPathWarning",
+]
+import sys
+
+from . import _tzpath
+from ._common import ZoneInfoNotFoundError
+from ._version import __version__
+
+try:
+    from ._czoneinfo import ZoneInfo
+except ImportError:  # pragma: nocover
+    from ._zoneinfo import ZoneInfo
+
+reset_tzpath = _tzpath.reset_tzpath
+available_timezones = _tzpath.available_timezones
+InvalidTZPathWarning = _tzpath.InvalidTZPathWarning
+
+if sys.version_info < (3, 7):
+    # Module-level __getattr__ was added in Python 3.7, so instead of lazily
+    # populating TZPATH on every access, we will register a callback with
+    # reset_tzpath to update the top-level tuple.
+    TZPATH = _tzpath.TZPATH
+
+    def _tzpath_callback(new_tzpath):
+        global TZPATH
+        TZPATH = new_tzpath
+
+    _tzpath.TZPATH_CALLBACKS.append(_tzpath_callback)
+    del _tzpath_callback
+
+else:
+
+    def __getattr__(name):
+        if name == "TZPATH":
+            return _tzpath.TZPATH
+        else:
+            raise AttributeError(
+                f"module {__name__!r} has no attribute {name!r}"
+            )
+
+
+def __dir__():
+    return sorted(list(globals()) + ["TZPATH"])